Level work supporting structure



Sept .'24, 1946. J F. HOFFER LEVEL WORK SUIVPORTING STRUCTURE :5 sheets-sheet 1 Filed Feb; 12, 1944 HHHQ wniilrlll a) INVENTOR. James fl/ affr w vf' rromwrs Q Sept. 24, 1946. Y

J. FIHOFFER LEVEL WORK SUPIfORTING STRUCTURE Filed Feb. 12, '1944 a snee ts-sheet-z i 5 o 9% \m. V .O.. N w a R \J 0 m .3 r 4 m a. 9 my Y u Q fl w em I fia fi f I l I I I I l .I. -ililiu Patented Sept. 24, 1946 James F. v,Ho'fier, -Detroit, Mich, assignor to" .811- a perdraulic Corporation, De'ai'born, Mich., "a corporation 'ofMichigan .:ApplicatiniFebruary 12; 19.44,-ISe1-'ial'No. 522;063

- 4 Claims.

, The present invention relatesto a work supporting structure and particularlyrelates to such a structure in which the work support is automatically maintained level.

*"Onejof the primary objects of the-present invention is to automatically maintain a work: support level-,with extreme ;accuracy regardless of any variations in level in the flooror ground Support p Another object of. theinvention is to-automatically maintain a work-support level through the action ofanovel float'controlled, fluid actuatedservo-mechanism. I

A 'further'obi'ect of theinvention is to provide animproved valve mechanism associated with the servo-mechanism. i

A further object of the invention is to provide an improved valve mechanism having a shiftable valve element in which .the efriction is reduced-between the valve element and the valve housing by effecting continuous rrela'tive rotation therebetween, thereby providing a sensitive and accurately responsive servo-mechanism.

A further object of theinvention isto 'provid avisual signal which indicates the relative rotation above mentioned. I

Other objects and advantages of theainvention will become clearly apparent from the following specification, the -drawings relating thereto, and fromthe claims hereinafter set forth. 7 a

- .In thedrawings, in which like numerals refer to like parts in the several viewsthroughout:

. Figurelis atop plan view of a work. supporting structure embodying features of the present invention; r v

Fig. 2 .is a front elevational view of the structure shqwn'inFig. 1;

Fig.3 is adiagrammatic-view orthe hydraulic circuit and its relationship to the servo-mechaniSm. 1 I

.Fig. 4isa vertical, cross-sectional-viewthrough one of the servo-mechanisms of the :present invention .and showing suchmechanism in its relationship tothe supporting surface;

..'Fig.; 5 is a cross-sectional view taken substantiallyalong the line- 5 01 Fig. 4;

M Fig; 6 -is-an'"enlarged,cross-sectional view-of that portion within th circle 6 of Fig. 4;

Fig. 7 is a cross-sectional viewtakensubstantially along theline 1-'-7of 1 ig.;4;

, -8 :is a .fragmentary, cross-sectional view taken substantiallyalong the .line .8--.8 of. Fig, hand 7 mounted'on the frame 42 at-the corners thereof.

According to the present invention, a-s tructure is provided by which a workpiece may be supported-and maintained lever-regardless of irregular-i-ties in the ground-or floor support. necessary and-desirablein -many fields, for ex? ample, in the airplaneassembly field.-- .Thereitis desirable to hold large subassemblies absolutely leve1 during the entire procedure'of-assembling the individual parts. The: structure of the present invention may-be either mounteddirectlyon the-floor, or it "may becarried on trucksalong trackways, or. supported merely by trucks; or ,the like. In any case, variations inthe levelof the ground supporting surfaceor trackways would 7 tend to disturb the level support-of the .WOl'kpiece, which is necessarily supported at numerous points-so that under those circumstances it would not, remain inaccurate alignment during assembly. With a structure ct -the present invention,

all of the supporting points of the workpiecewill remain in .accurate relation :regard-lessf-o-f any" variations in levelness of the supporting ground ortrack. Referring to the drawings, a flat table member I0 is mounted on a frame [2 and interconnected thereto-through servo-mechanisms generally indicated'at l4. Intheembodiment illustrated, the table Land frame-'1 2 aretriangular in shape with three-:servo-mechanisms Myone located at each corner and fixed to platemembers 1.6, which are Through the action of the servo-mechanisms, to be described in detail hereinafter, the table II] is maintained absolutely-level regardless of any ti'ltingof the frame 12. j

Each servo-mechanism includes a base 18 forming a receptacle for a bath of liquid, such as oil. The base I8 is secured to a plate lliby means o'f bolts or the like. An upper housing member 2!] is removably secured to the top edge of the base 18 and is formed to provide an vupwardly directed :cylinder chamber 22. A depending central portion 24 is formed integral with the housin :20 centrally thereofan'dwisv forced 'with a vertical central bore 26. The upper the lower end opens into the space above receptacle +8. -A -pis ton 28 .is'slidably :disposed within chamber 22 :and is formed with an annular recess 30 on the periphery thereof within which anannular synthetic rubber ring 321s ;Fig'. 9 is ,a vertical, cross-sectional view of a 7 disposed. .:Such ring 3,2 is circular incross-section and sealably engages the wall of chamber '22 as the piston 28 slides therein. 7 The integral'upper end 34 of piston 2 I I 8 extends through a sealed opening in'an end cap 36 which .stem 54.

46 is received through an opening 48 in table I0.

and the undersurface of table I rests upon a top flat surface of a supporting member 50; Such supporting member 50 is formed with a central opening therethrough' through which the pin 46 passes with a loose fit. The undersurface 52 of member 50 is formed complementary in shape to the shape of the dished recess .44 so that the member 50 may tilt slightly with respect to piston portion 34 for properly supporting the table I0.

The piston 28 is also formed with a] dependin stem 54, which is slidably received within bore 26; r The stem 54 is formed with chambers, ports and passageways for the flow of fluid therethrough and for the reception of a valve element to control the flow therethrough. A reduced annular portion 56 is formed on stem 54 to provide an inlet chamber which receives fluid through passageway 58 and port 60 formed in housing 20. A filter 62 is disposed in passageway 58 to filter the oil passed therethrough. The passageway 58 is connected to asource 'of fluid under pressure in a manner that will be described hereinafter.

A vertical passageway 64 is formed in stem 5.4 and communicates through passageway 66 with the annular chamber 56. A passageway 68 communicates with passageway 64 andalso communicates with central bore I0 formed in Anotherlvertical passageway I2 is formed in stem 54 and communicates with bore I0 through passageway I4 and also communicateswith'an annular chamber "I6, formed by reduced portion I8. of stem 54, through passageway 80. The chamber I6 communicates with the cylinder chamber 22 on the underside of piston 28.

Another passageway 82 is formed in stem 54' and communicates with another passageway '84 formed on stem 54, which passageway 84 also communicates through opening 86 with the interior of a tubular jet member 88. Such tubular member 88 is fitted to the lower end of stem 54 and the outer end thereof is formed to provide a tangential jet outlet 90, as best shown in Fig. 8. The purpose of the tubular member 88 and the jet outlet will be described hereinafter. h

The outer ends of passageways 64,68, I2,- 82

and 84 may be closed by ball plugs 92, with the 1 adjacent surfaces of stem 54 peened thereover.

The chamber 56 is sealed with respect to bore 26 by means of upper and lower sealing rings 94 which are disposed in annular grooves formed in stem 54. The arrangement of passageways 68, I4 and 82' with respect to each other is as shown and a control of the flow of fluid there-- between is efiected by means of a valve element generally'indicated at 96. Such valve element 96 is slidably disposed within bore I0 and is' formed at its upper and lower ends with land surfaces Which slidably engage the sides of the bore I0. Certain portions of thevalve element, 96 are shown in enlarged form in Fig. 6 and certain of the dimensions are exag erated for the purpose of clear illustration. The valve element 96 is formed with reduced annular portions 98 and I00. Stem 54 is providedwith an enlarged recess forming an annular chamber I02, such annular chamber being located below passageway 82, above passageway 60, and in direct communication with passageway I4. The valve element 96 is formed with a pair of annular valve portions I04 and I06. The shoulders formed by the chamber I02 define annular valve surfaces I08 and H0. The diameter of valve portion I04 is such that the lower annular edge H2 thereof will seat against valve surface I08 to prevent the passage of fluid thereacross when in its seated position. The diameter of valve portion I06 is smaller than that of valve portion I04'and'the upper annular edge H4 thereof is disposed so that it will not entirely out off the flow of fluid past valve'surface I ID in any of its positions, but will vary the resistance to flow past the valve surface I08 as'the relative positions of the valve surface H0 and valve portion I06 vary with respect to each other.

The lower end of valve element 96- extends downwardlythrough the lower end ofbore I0 and is connected to a float H6. In order to limit the relative movement between valve element 96 and bore 10, the valve element has an enlarged annular shoulder H8 which is received within an annular recess I20 formed adjacent the lower end of bore 12. v A stop ring I22 is fixed in position adjacent the "enlarged recess I20 to limit relative movement inone direction while the adjacent shoulder of the-recess limits movement in the opposite direction. The lower end of valve element 96 is fixed to "the float H6 so that it occupies the same vertical position as the float and so that it will rotate as the float rotates. The float H6 is supported in a bath of fluid, such as oil, the level of which is indicated generally at I24. All of the receptacles I8 are in open communication with each other through interconnecting pipes I26, one of the pipes'l26 having a tank or reservoir I 28 connected therein and in open communication with that particular pipe I 26. The levelof the fluid in all of the receptacles I8 will thu always be the same so that the floats H6 may be considered as being disposed in a common bath of fluid.

So as to effect an accurate and sensitive action of the valve element 96 to control the flow of fluid, friction between the valve element 96- and the wall of bore I0 is reduced by rotating the valve element 96 with respect to bore 10. Such rotation is effected by rotating the float H6. An upwardly'extending skirt I28 is secured to the float H6 around the peripheral edge thereof and extends above th top surface thereof. A ring member I30 is also'connected to member I28 and float H6 andis formed with in-struck tabs I32 therearound which form rotor or turbine blades against which the fluid from jet impinges to cause rotation of "the float H6 and, therefore, rotation of the valve element 96. Drain openings I34 are formed through members I28 and I30 at spaced intervals the'rearound so that the fluid directed against the vanes I32 may drain back to the receptacle. f

In order thatan' attendant may be instantly apprized of the fact that the valve element 96 is rotating, a visual signal is provided which will indicate such rotation and will indicate whethersuch rotation has stopped. Such means are best amazes with suitable electricconnections tor I lately leach Themanneninwhich. eachof the of; the bulbs polars-so. located-aside serve-1nechanism ;v It acts. or operates. to. main directhe naeainsttheiacingendlit-eiafiui tain the lerei, condition is. the Same for 311cm ales: on-Luoiterod. I144. SucheBlex-iglas. and-Lucite such.- mecnanismsand a description for on will are well known. of. thermoplastic? material 5- be; sumcient; for an understanding; of all.v It will which transmit. light. rays and. e 5.0 be appreciatedthat. all of the floats. I-I-B are disthattherodextends upwarmythrouehcpening. posed in a common; bath so that the are; all [.46 pnovidcd; in. housing; 2.0; and; then: extends maintainedat the,- same: level, thus. maintaining completely around the housingwithinsanannulas the-@valve;elements afi.atthe same level. Hy ra l grooveiorrnedtherein .on .the.outside.. Theiouter 1.0 fluidnnderpressure,issuppliedpassageway 58am].- edgernay thenbe ggtoundrflat asshownat; I48. It chamber 22 under piston 28;- wilL be filled withoil in one-oi the, properties. of thi materiakthanlight witl-rtheg pistongin. theapproximate positionin.- reefs.impinging;against,surtace I:.42.'wil1:be-.visible dicated in Fig. 4.. Ati-lting down of; one of the on. the roughened. surface I.4;8-.. A shutter? 01: corners of the-rfra-meewouldgeausea corresponding screen L50.informed.withiamupstanding,central. downward movementof receptacle.- I8 and house portion having cutawaysections. I52- betweenthe ing; and-,gwhile the, absolute level. of. theliquid upstanding; screen-section I50.. Sucnupstande remainasubstantiallythe same, the-depth ofthe ing; sec ions. are.- disnosed. tonnes. betweensuriace liqnidin'receptacle I8; is increased. This increase I42: andbulb. Mil-as, the-float H6 rotatesrso tha't indepthpcauses the. float to ris with-therresult, sections. I50=will-. intermittently blankthe direce zo thatthevalvesurface I08;mo.ves, away fromvalve tion oLlig-ht. rays against surf-ace I42- This will edge [ill-so; that; the-fluid-under pressu-rerwollld be indicated: by a blinking/onsurface: I48. In the pass from passageway 58, through passageway, eyentthat the. blinking stops. it will anonce be intochamber 56, through.passageways66; 64, and apparent thatthe rotation of the valve-element. 68,, past valveasurface II;2,, intopassageways. [4, has stoppedindicating; excessive-friction invalve, 2 5 1.2-, 80.- a-ndinto, chamber; 16. and from: there into failurezof hydraulicvpressure etc. Accesstdthe chamber: 22 under piston. 2-8, thus raising; the interior ofthereceptacle I-8maybe-had-thmugh piston.- 2-8. At thesametime, fluidisrpassin'g from an opening I54 having a transparent-removable chamber I 0.2-.past valvesurface I.I-0 -into passagewindowtlili associated therewith. waxt82. The. fluid fromsuch. passageway. then A source of fluid under pressure is constantly 3,0 passesthrongh passage 8.4into.and-.through tubue supplied each of the passageways 58 of each of lar jet member 88 and through the jet opening the mechanisms I4. Such source comprises a '90 so that it impinges against the vanes I32 to pump I60 having the inlet end thereof commucause the valve 96 to rotate. The passage of fluid nicating with tank I28 and having the outlet end into chamber 22 would cause the piston 28 to thereof communicate through a pressure relief raise so that the valve surface I08 would move valve I62 with each of three branch lines I64. to a position adjacent valve surface I I2 to shut Each of the branch lines I64 is attached to the off the flow of fluid from passageway 68. .Any opening into passageway 58. The pump is driven tendency on the part of the table I0 to lower by a suitable prime mover such as an electric would cause piston 28 to move downwardly so that motor I66. The relief valve I62 communicates fluid from chamber 22 would pass into chamber back to the tank through a return conduit I68, as I6 and through passageways 80, I2, and I4 into is usual in hydraulic circuits. Suitable means chamber I02 and past valve surface IIO through may be provided within tank I28 to prevent turpassageway 82. The fluid from the passageway bulence therein, and also suitable means may be 82 then passes through the jet against the smooth provided to filter the oil to the inlet to the pump. annular surface above the blades I32 to cause the Housing 20 is formed with a vertical passagevalve to rotate as mentioned above. By directing way "0 which communicates at its lower end the stream against the smooth surface itis spread with the space above receptacle I8 and commuover a relatively large area and flows down nicates at its upper end through a passageway against the blades in a tangential direction so "2 with the chamber 22 above piston 28 so as to that a smooth rotative action is attained. The vent or return any fluid which may have leaked valve edge II2 may be considered as'the control past piston 28 to the reservoir. edge and, in a balanced condition, it will be very In the embodiment illustrated, the frame I2 is slightly removed from seating contact with valve shown as being supported upon the ground or seat I08. The relative linear movement between floor surface. In order to effect an approximate valve 06 and piston stem 54 is very slight, in the leveling of the device, screw jacks I80 are disneighborhood of a few thousandths of an inch, posed adjacent each corner of the frame. While so that the control is very accurate with a conin the embodiment illlustrated, three jacks are stant flow of fluid past valve surface IIO either shown, any number may be used, if desired. from port 68 or port I4. The slightest variations However, it is to be understood that such frame in levels at the corners of the frame will thus be I2 might just as well be supported on trucks instantly reflected in any of the servo-mechanrunning on a trackway or on trucks having isms which instantly act to compensate for such ground-engaging wheels. As mentioned above, variations in tilting of the frame.

if there is y unevenness in the ground flO It is to :be understood that within the broader surface or in the trackways ausi g a t g of aspects of the present invention a single'servoframe I2, the servo-mechanisms I4 automatimechanism I 4 could be employed in which event cally act to maintain the support I0 level the projecting end of the plunger 3-4 would serve In the operation of the device above described, as a supporting b the work article is supported upon the table I0. w t claimedis;

The frame which may be Supported as 70 1. A device ofthe type described comprising a scribed above, may not be level so that each of supporting member a fl at disposed in a bath the three corners of the rame ay e diSDOSBd of liquid, and a fluid servo-mechanism interconat different levels. In t t eve t. t e SerVO- necting said float with said member, said mechmechanisms of each of the corners will autoanism including a cylinder, a piston disposed matically act t maintain the S ppo t I abSO- 7 therein and connected to said supporting memher, a pair of cooperating and relatively shiftable valve elements, one of said valve elements being connected to saidpiston and the other to said float, and means to supply fluid under pressure past said valve elements, said valve elements being so constructed and arranged that fluid'is continuously passed to atmosphere.

2. A device of the type described comprising a supporting member, a float disposed in a bath of liquid, and a fluid servo-mechanism interconnectme; said float with said member, said mechanism including a cylinder, a piston disposed therein and connected to said supporting member, a pair of cooperating and relatively shiftable valve elements, one of said valve elementsbeing connected to said piston and the other to said float, and means to supply fluid under pressure past said valve elements, said valve elements being so constructed and arranged that fluid is continuously passed to atmosphere and 'for certain positions of said valve a portion of said fluid is passed to said cylinder.

3. A device of the type described comprising a supporting member, a float disposed in a bath of liquid, and a fluid servo-mechanism interconnecting said float with said member, said mechanism including a cylinder, a piston disposed therein and connected to said supporting member, a pair of cooperating valve elements shiftable relative to each other in 'a linear direction,

one of said valve elementsbeingconnected to said piston and the other-"t0 said float, means to supply'fluid under pressure past said valve elements, said'valve elements being so constructed and arranged'that fluid is continuously passed to atmosphere, and means disposed in the path of the fluid passed-to atmosphere and connected to one of said valve elements to continuously rotate said one of said valve elements.

4. A device of the type described comprising a supporting member, a float disposed in a bath of liquid, and a fluid servo-mechanism interconnecting said float with said member, said mechanism including a cylinder, a piston disposed therein and connected to said supporting member, a pair of cooperating valve elements shiftable relative to each other in a linear direction, one of said valve elements being connected to said piston and the other to said float, means to supply fluid under pressure past said valve elements, said valve elements being so'constructed and arranged that fluid is continuously passed to atmosphere and for certain positions of said valve a portion of said fluid is passed to said cylinder, and means disposed in the path of the fluid passed to atmosphere and connected to one of said valve elements to continuously rotate said one of said valve elements. I "JAMES F. HOFFER. 

